Conditionally Passing Different Values to Template Parameters in Azure DevOps Pipelines

Parameters Azure pipeline template helps to achieve dynamic behaviours in pipeline templates. Passing different values for template parameters based on conditions, via a single usage of teplate will help to reduce duplication of usage of template in the pipeline. Let's look at how to conditionally pass different values to template paramters with a practical example.

The expected behavoir

Let's assume there are three stages in the pipeline.

• Unit test stage - to build and unit test
• Build and push Docker image stage
• Deploy app stage

If we are in develop branch (refs/heads/develop) we want to run unit tests, build dcoker image and depending on both stages want to run a deploy.

Passing Environment Variables to Reusable Workflows in GitHub Actions

 We have discueed, that we have to use an environment variable to handle input parameter default values, if we are using trigger for workflow on push in the post "Setting Workflow Environment Variable Based on Input Parameter in GitHub Actions - on workflow_dispatch and Use a Default Value on push". If we have to pass on the input paramter value from a workflow to a reusable workflow, it does not work as expected and it is a limitation of reusable workflows  as explained in here. Let's try to understand with an example how to pass an env variable to a reusable workflow.

Setting Workflow Environment Variable Based on Input Parameter in GitHub Actions - on workflow_dispatch and Use a Default Value on push

 GitHub actions workflows support input only on manual trigger workflow_dispatch. What if we need to use default value in other triggers such as on push and use input parameter in case of manual trigger workflow_dispatch? Let's explore our options with an example.

Using Object Type Azure DevOps YAML Pipeline Parameter in PowerShell Task

 Using a YAML pipeline paramter in a PowerShell task is straight forward for types such as string. For example, if there is a YAML pipeline parameter named env of type string, we can read it in PowerShell task with $envName = '${{ parameters.env }}; without any issue. However, if the parameter is type of object we cannot read, the paramter the same way we do with string parameters. If we try to read object parameter named apps, $apps = '${{ parameters.apps}}; , there will be an YAML validation error staring the pipeline such as below. 

/azure-pipelines.yml (Line: 57, Col: 23): Unable to convert from Array to String. Value: Array

Even if we try to use below it will be same issue.

[String[]]$apps = '${{ parameters.apps}};

[PSObject[]]$apps = '${{ parameters.apps}};

Let's explore the issueand solution in detail.

Use Template Parameter to Create Array in Bash Task in Azure Pipelines

 Converting Azure pipeline parameter type of object, which contain an array of strings, to an array object in bash script task is not clearly documented. We can use the join expression for Azure pipeline tasks to achive this requirement. Let's look at how to do with an example.

Passing Output Parameters from Bicep Modules

 We have discussed about deploying resources to a resource group using Azure Bicep in the post "Azure Infrastructure as Code (IaC) with Bicep - Creating Resources in Resource Group". If we are referring a resource created via a module in another module, we might have to pass identification of such resources as output parameters from a module. Let's learn how to pass output parameters in Bicep modules and use them in other resources in this post.

Azure Service Connection via Variable Group in YAML CD/Release Pipeline Templates

In application deployment we may use different Azure subscriptions to setup infrastructure for non-prod and production environment infrastructure most of the time. In classic release pipelines we could easily create a resource group to setup deployment task needs, which should be used in multiples stages/environments such as Dev, QA, staging or production. For such groups when the task group is using Azure App Service Deployment, Azure CLI tasks we could supply the service connection name via a variable that can be stored in a variable group relevant to the given stage/environment scope. In YAML we can use a template to define the common steps and it is ideal if we could refer to variable group, to hold the service connection information related to the relevant stage/environment. However, the possibility to use the variable group variable for service connection, regardless of whether using a template in YAML or Azure deploy steps used directly in pipeline YAML seems to be not working as expected. Let’s look at the problem and alternative solutions.

Making a Task Group Parameter Optional – Azure DevOps Pipelines

Task groups are really useful to share common actions with multiple build or release pipelines in Azure DevOps (VSTS). You can group multiple tasks ang create a task group forma build or release definition. then these task groups can be utilized in other build or release definitions in a given team project. Parameters in a task group help to pass values from build or release definition to the tasks in the task group. You can add a default value for these parameters or have to provide value from the build or release definition that is using the task group. Making a task group parameter optional is not straight forward and you need some do work around to get it working. Let’s look at how we can make a parameter optional for a task group in Azure DevOps pipelines.